Gassing was slowly evaporated in vacuo material phenomenon is a major problem on the vacuum performance considerations. In the vacuum system, the surface of any solid material, may exist molecular layers formed by the accumulation of liquids and gases, which decrease the molecular layer as the pressure is gradually evaporated. Inert gases and volatile solvents deflated relatively faster speed, water vapor and oil will be attached to the surface, it will evaporate in a few hours before. Dust particles, porous materials and other foreign matter will increase the surface area of the system, which can lead to more deflation appear.

Temperature and radiation absorption of some molecules will provide sufficient energy away from the surface. Elevated furnace temperatures will gradually release the original at low temperatures will remain on the surface of the molecule. Thus, with the stove heating, gas discharge phenomenon will increase. The furnace temperature is lowered or kept constant temperature can mitigate this.

Kept clean is the key to reducing deflated. Further, with an inert gas or nitrogen purged to exclude air inside, the system can be avoided when the surface exposed to air vapor film is formed. After the furnace chamber is opened, its internal for heating can also achieve this effect. To minimize the number of the cavity opening, particularly in wet weather, does not appear to reduce gassing and improve the performance of vacuum annealing furnace.

2, taking the time to rate

Pumping speed is at atmospheric pressure when the furnace chamber, the vacuum valve is opened, the vacuum chamber reaches a predetermined pressure, time, is (including re-quality gas suction) system performance measuring method at any pressure. In order to obtain reproducible resistance, furnace chamber should be cleaned, drained and deflated, and each pump has been running for a sufficient time to reach full pumping speed.

3, ultimate vacuum

Ultimate vacuum is actually completed deflated acquired vacuum state, the ability of a predetermined pressure of the exhaust gas flow and then the leakage caused by the vacuum suction system balance. To maintain accuracy, vacuum measuring instruments must be sufficiently sensitive and accurate after calibration.

The furnace was raised to its maximum degree ju, accelerating deflation system. After the furnace is heated and cooled to room temperature under vacuum, can be measured true ultimate vacuum and leak rate. Ultimate vacuum pump called "extreme low pressure" is a good way to get pumping system isolation performance.

4, the leakage rate

Leak rate is the closed vacuum chamber when the vacuum pressure rise rate, includes two aspects: the leakage rate and the discharge rate of gas. Leak rate is the actual cabin pressure gas through leaks caused by increase in the flow, is constant; gassing rate (including virtual drain) with the tank empty, gradually approaches zero. Virtual volume vacuum leak is entrained bulkhead, slowly leaking gas into the cabin.

Leak rate per hour of micrometers of mercury (mmHg) value, typically measured one hour, the leakage rate of not more than 5mmHg hour. When measuring the cavity pressure rise rate, emptying the furnace chamber and start the cycle heating, the heating is stopped after the completion of the discharge gas until the pressure remains constant (ultimate vacuum), and then close all the vacuum valve, press the stop button isolate circulating oven cavity. This caused the valve to minimize the impact of the closure, while allowing the vacuum system to reach equilibrium. After one hour, the vacuum was measured again to calculate the rise in pressure per unit time. For example: if the initial pressure was measured 5mmHg, after one hour of 8mmHg, then the rise velocity per hour 3mmHg.

What is the vacuum
Vacuum means that a given gas pressure within the space of less than the area of a standard atmospheric pressure gas state.
Vacuum is rarefied gas environment. Compared with the atmosphere it has a number of advantages, such as gas thin, less oxygen, clean environment...

Vacuum pump in a variety of different job categories effect have?
Vacuum pumps work in a variety of different play areas in effect summed up in the following areas:
1, main pump: the so-called main pump is a vacuum system is evacuated container is directly evacuated to the vacuum pump ...